The overall goal of this research is to validate and apply an optical coherence tomography (OCT) imaging method for assessing stress, strain and compliance in coronary vessels in vivo. Acute myocardial infarction, the leading cause of death in industrialized countries, is frequently caused by rupture of a coronary atherosclerotic plaque. Current understanding of the relationship between biological, biochemical, and mechanical factors associated with rupture, however, is incomplete. We will develop and test a novel method that incorporates both fmite element analysis and intravascular elastography measurements with OCT to accurately assess vessel elastic properties. The proposed research will investigate the utility of our method to enhance the modeling of stress, strain and compliance in vessels from model systems to animal vasculature. We hypothesize that determining the elastic properties of vessels with our method will permit realistic modeling of vessel stress, strain and compliance in response to linear forces and pressures. The accuracy of our method will be assessed in models of graded pressure and localized forces. Subsequently, we will use the method to monitor vessel mechanical properties in a rabbit model of atherosclerosis. Principal stress, principal strain and tissue compliance will be monitored over time during plaque progression and during response to lipid lowering therapy. At sacrifice, these results will be correlated with histological fmdings. Our hypotheses are that 1) locations of elevated stress in lipid rich plaques become more compliant during plaque progression, and 2) stress and compliance in lipid rich plaques decrease in response to lipid-lowering therapy. The methods that will be developed in this work present the potential for characterizing the biomechanical properties of coronary plaques in vivo and may facilitate the development of improved therapeutic approaches.